/*
 * Copyright 2013-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.cloud.gateway.discovery;

import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.cloud.client.discovery.ReactiveDiscoveryClient;
import org.springframework.cloud.client.discovery.composite.CompositeDiscoveryClientAutoConfiguration;
import org.springframework.cloud.gateway.config.GatewayAutoConfiguration;
import org.springframework.cloud.gateway.filter.FilterDefinition;
import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory;
import org.springframework.cloud.gateway.handler.predicate.PathRoutePredicateFactory;
import org.springframework.cloud.gateway.handler.predicate.PredicateDefinition;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.DispatcherHandler;

import java.util.ArrayList;
import java.util.List;

import static org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory.REGEXP_KEY;
import static org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory.REPLACEMENT_KEY;
import static org.springframework.cloud.gateway.handler.predicate.RoutePredicateFactory.PATTERN_KEY;
import static org.springframework.cloud.gateway.support.NameUtils.normalizeFilterFactoryName;
import static org.springframework.cloud.gateway.support.NameUtils.normalizeRoutePredicateName;

/**
 * 重写默认理由规则，使得微服务下访问地址与单应用下访问地址相同
 *
 * @author 张智研
 * @date 2022/09/02 14:44
 */
@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@AutoConfigureBefore(GatewayAutoConfiguration.class)
@AutoConfigureAfter(CompositeDiscoveryClientAutoConfiguration.class)
@ConditionalOnClass({ DispatcherHandler.class, CompositeDiscoveryClientAutoConfiguration.class })
@EnableConfigurationProperties
public class GatewayDiscoveryClientAutoConfiguration {

    public static List<PredicateDefinition> initPredicates() {
        ArrayList<PredicateDefinition> definitions = new ArrayList<>();

        // add a predicate that matches the url at /serviceId/**
        PredicateDefinition predicate = new PredicateDefinition();
        predicate.setName(normalizeRoutePredicateName(PathRoutePredicateFactory.class));
        predicate.addArg(PATTERN_KEY, "'/'+serviceId+'/**'");
        definitions.add(predicate);
        return definitions;
    }

    public static List<FilterDefinition> initFilters() {
        ArrayList<FilterDefinition> definitions = new ArrayList<>();

        // add a filter that removes /serviceId by default
        FilterDefinition filter = new FilterDefinition();
        filter.setName(normalizeFilterFactoryName(RewritePathGatewayFilterFactory.class));
        String regex = "'/' + serviceId + '/?(?<remaining>.*)'";
        String replacement = "'/' + serviceId + '/${remaining}'";
        filter.addArg(REGEXP_KEY, regex);
        filter.addArg(REPLACEMENT_KEY, replacement);
        definitions.add(filter);

        return definitions;
    }

    @Bean
    public DiscoveryLocatorProperties discoveryLocatorProperties() {
        DiscoveryLocatorProperties properties = new DiscoveryLocatorProperties();
        properties.setPredicates(initPredicates());
        properties.setFilters(initFilters());
        return properties;
    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnProperty(value = "spring.cloud.discovery.reactive.enabled", matchIfMissing = true)
    public static class ReactiveDiscoveryClientRouteDefinitionLocatorConfiguration {

        @Bean
        @ConditionalOnProperty(name = "spring.cloud.gateway.discovery.locator.enabled")
        public DiscoveryClientRouteDefinitionLocator discoveryClientRouteDefinitionLocator(
                ReactiveDiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
            return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);
        }

    }

}
